On Growing Lilacs
by Rose "No, I'm Not Related to George" Bush

Recommended Book from Amazon

Lilacs for the Garden
By
Jennifer BennettLilacs are lovely. They are famous for their visual splendor in the garden and for their fragrance, a favorite among flower-lovers everywhere. They even have a color named after them ... that dusky pale gray-purple color grandmothers especially seem to love. Lilacs the flowers actually come in a range of purples, from almost a grape color to lavender ... and even white.
They can and will bloom profusely, but the flowering season for them is short -- about two to six weeks as a rule. The weather has a lot to do with it ... and a cool, dry spell once the flowers start means a longer season. Sadly, the flowers wilt within a couple of days when cut and brought inside for bouquets. None of the usual tricks seems to work -- crushing the stems, adding preservatives to the water, using warm water. The best you can do is keep them in a cool spot away from direct sunlight. You just have to enjoy them while they last. But still they are worth it.
It can take two or three years to get them established, but once they are set, the shrubs themselves are sturdy and strong. They grow tall, require moderate to minimal care. They provide a terrific hedge for a windbreak or extra privacy, and once established, the plants will almost certainly outlive you. Some sources claim there are lilac bushes in New England originally planted in colonial times. So, yes, once you put them in, you can expect them to last although they may need supplemental water to see them through especially long dry spells.!
Lilacs do best in full sun, but they can grow in light shade. They like a well-drained, slightly acid to alkaline soil. To encourage blossoms -- which is a big reason to have lilacs after all, there are commercial bloom boosters you can try. Do take off the spent flowers every year and cut the flowering stem back to a set of leaves to stop the plant from putting energy into producing seeds rather than next year's flowers. If you don't, next year's array of blossoms may be disappointing.
Recommended Book from Amazon

Lilacs: The Genus Syringa
By
John L. FialaLilacs also need a lot of nutrients and can deplete a soil that is not well maintained. Be sure to use a good mulch of well-rotted manure and plenty of appropriate fertilizer. Thin your shrubs from time to time, taking unproductive stems (the thick trunks of old growth) when your older bushes become too dense with branches and sucker stems.
Prune lilacs right after they bloom. This is not just the best time, it's the only right time. Lilacs bloom only on old wood from the previous season. If you prune sometime other than right after they flower, you're cutting off next year's blossoms. To keep your shrub properly shaped, sized and groomed, remove 1/3 of the old wood each year at ground level -- again right after the end of blooming season -- and shape your bush over a number of years. If you prune in the fall, you're taking off next year's gorgeous flowers with every cut.
Some shrubs, like many hydrangeas, on the other hand, can be pruned safely in the fall, because they bloom exclusively each year on new wood. For lilacs, though, cut the old tree-like trunks right at the ground. New shoots -- suckers -- will then grow from the base of the plant. At the end of three years, you'll have a fully rejuvenated plant -- producing flowers at nose level, right where you want them! Yes, the entire shrub can be cut to the ground -- if you find you have to do that for any reason. But this is very hard on the plant and destroys any chance of flowers for several years after this radical surgery.
You can put lilacs temporarily in large containers and keep them there a year or so before transplanting them to their permanent home, but their size makes it impractical to try keeping them confined there longer. The good news is, they are easy to transplant successfully. Spring is the best time, and you may have to just accept a year without blooms immediately afterwards to let the plant recover from transplant shock. When you choose their final home, make sure they get full sun and plenty of room. Lime in the soil every year insures a bumper crop of blossoms.
If you notice a white, powdery substance on the leaves of your lilacs, especially in late summer and early fall, the culprit is probably a leaf mold called "downy mildew" or "powdery mildew." It's a fungus, and a fungicide will kill it. It shows up when conditions are moist and humid enough for the mold to get started -- like after a spell of constant rain. When watering lilacs, avoid spraying their leaves. Powdery mildew on lilacs is more unsightly than harmful.

You can buy these gorgeous shrubs (and lots more!!) here.
They also have a sign-up page for a free catalog.
Nature Hills Nursery
One of the best sites for more information on lilacs is here
The Gardener's Network
How to Grow and Care for Lilac Bushes